Method for determining gravity potential and elevation by GNSS carrier phase inter-station single-difference time-frequency transfer

Abstract

This application relates to a method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer. The method includes: using a high-performance atomic clock as the reference clock for the GNSS receiver, providing the GNSS receiver with a high-precision and high-stability time and frequency reference; conducting high-precision GNSS observations; directly calculating the clock difference between two GNSS stations using GNSS inter-station single-difference carrier phase time-frequency transfer technology; extracting gravity frequency shift information between the two stations; and then determining the gravity potential difference between the two stations based on the gravity frequency shift formula to achieve cross-sea altitude measurement. This solves the problems of existing technologies, such as the difficulty in eliminating the influence of satellite-end errors on GNSS time-frequency transfer, the inability to overcome the limitations of traditional gravity potential measurement technologies, and the difficulty in achieving a unified global altitude benchmark.

Description

Technical Field

[0001] This application relates to the fields of geodesy and geophysics, and in particular to a method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer. Background Technology

[0002] Gravitational potential is a fundamental element of the gravitational field, which is one of the basic physical fields and has significant scientific and applied value in many disciplines, including seismology, geodynamics, aerospace, meteorology, oceanography, natural disaster research, and global change. Furthermore, gravitational potential plays a crucial role in national defense and economic development. Traditional methods for determining gravitational potential require combining gravity measurements and leveling. However, leveling over long distances consumes substantial human and material resources, has a lengthy measurement cycle, and accumulates errors as the transmission route increases. Gravitational potential measurements become extremely difficult, especially in mountainous areas. Moreover, this method is limited by its inability to perform cross-ocean measurements, restricting the standardization of global elevation benchmarks.

[0003] To address the aforementioned problems, existing methods for measuring gravitational potential based on the principles of general relativity, such as Einstein's theory of general relativity, explain that the clock speed and the frequency of electromagnetic signals change with gravitational potential (altitude). In other words, clocks at two locations with different gravitational potentials run at different speeds. If a frequency signal is transmitted between these two points, the frequency at the time of transmission will differ from the frequency at the time of reception. Based on this principle, existing technology can use a relativistic method to measure the difference in gravitational potential. The core idea of ​​this method is to utilize the correspondence between the difference in gravitational potential and the difference in the speed or frequency of a precision clock. By transmitting time and frequency data, the difference in gravitational potential between two locations can be observed. This method is expected to achieve a significant breakthrough in overcoming the challenges faced by traditional measurement methods.

[0004] With the rapid development of precision clock manufacturing technology, the accuracy in ground-based laboratories can now reach 1000 rpm within hours. -19 ~10- 20 The magnitude is on the order of magnitude, and portable high-precision optical clocks have also reached 10. -18 The magnitude of these optical fibers makes high-precision relativistic gravitational potential measurements possible. Given the high precision of optical fibers and cables, existing techniques have been used to compare the frequencies or times of atomic clocks at two locations by connecting them with optical fibers or cables, leading to a series of experiments determining the gravitational potential difference between the two locations. However, due to geographical factors and the cost of laying optical fibers or cables, the application of this method in long-baseline and transoceanic situations is limited.

[0005] In summary, existing technologies are insufficient to eliminate the impact of satellite-end errors on GNSS time and frequency transmission, cannot overcome the limitations of traditional gravity potential measurement technologies, and are difficult to achieve a unified global elevation benchmark, which urgently needs to be addressed. Summary of the Invention

[0006] This application provides a method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer, in order to solve the problems of existing technologies that are unable to eliminate the influence of satellite-end errors on GNSS time-frequency transfer, cannot overcome the limitations of traditional gravity potential measurement technology, and are difficult to achieve a unified global elevation benchmark.

[0007] The first aspect of this application provides a method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer, comprising the following steps: performing co-location observations using two co-located GNSS observation stations set at the same site to obtain co-location GNSS observation data for each of the two co-located GNSS observation stations; performing remote comparison observations using two remote GNSS observation stations set at different sites to obtain remote GNSS observation data for each of the two remote GNSS observation stations; and performing the method based on a preset GNSS carrier phase time-frequency transfer strategy. The co-located GNSS observation data and the remote GNSS observation data are subjected to GNSS inter-station single-difference processing to obtain clock error sequences during the co-located observation and remote comparison observation processes. Based on the clock error sequences, the inherent frequency difference corresponding to the co-located observation and the remote observation frequency difference corresponding to the remote comparison observation are calculated. The gravity frequency shift corresponding to the remote comparison observation is then calculated using the inherent frequency difference and the remote observation frequency difference. The gravity potential difference between the two remote GNSS observation stations is calculated based on the gravity frequency shift and a preset gravity frequency shift formula. The gravity potential and altitude values ​​of each remote GNSS observation station are then calculated using the gravity potential difference.

[0008] Optionally, in one embodiment of this application, the step of performing GNSS inter-station single-difference processing on the co-located GNSS observation data and the remote GNSS observation data based on a preset GNSS carrier phase time-frequency transfer strategy to obtain clock difference sequences during co-located observation and remote comparison observation, and calculating the inherent frequency difference corresponding to the co-located observation and the remote observation frequency difference corresponding to the remote comparison observation based on the clock difference sequences, so as to calculate the gravity frequency shift corresponding to the remote comparison observation through the inherent frequency difference and the remote observation frequency difference, includes: obtaining the GNSS pseudorange and carrier phase observation equations corresponding to the two remote GNSS observation stations based on the co-located GNSS observation data and the remote GNSS observation data; and based on the GNSS carrier phase time-frequency transfer strategy and the GNSS pseudorange and carrier phase... An observation equation is constructed to establish a GNSS inter-station single-difference carrier phase time-frequency transfer model. This model is used to perform GNSS inter-station single-difference processing on both the co-located GNSS observation data and the remote GNSS observation data, resulting in clock bias sequences during co-located observation and remote comparison observation. Data processing is then performed on these clock bias sequences to obtain a standard clock bias sequence. Based on the standard clock bias sequence and a preset clock bias-frequency difference conversion relationship, the inherent frequency difference during co-located observation and the remote observation frequency difference are calculated. Finally, the inherent frequency difference in the remote observation frequency difference is removed to obtain the gravity frequency shift during the remote comparison observation process between the two remote GNSS observation stations.

[0009] Optionally, in one embodiment of this application, the step of calculating the gravity potential difference between the two remote GNSS observation stations based on the gravity frequency shift and a preset gravity frequency shift formula, and using the gravity potential difference to calculate the gravity potential and altitude of each remote GNSS observation station, includes: obtaining the gravity potential and altitude of the target mobile station of the target mobile station among the two remote GNSS observation stations; substituting the gravity frequency shift into the gravity frequency shift formula to obtain the gravity potential difference between the two remote GNSS observation stations, and calculating the gravity potential of the target reference station based on the gravity potential difference and the gravity potential of the target mobile station; determining whether the two remote GNSS observation stations are transferring elevation within the same elevation datum, and if the two remote GNSS observation stations are transferring elevation within the same elevation datum... For elevation transfer, the terrain information of the areas where the target mobile station and the target reference station are located is determined, and the gravity equipotential surface corresponding to the terrain information is calculated using the gravity potential. Based on the gravity equipotential surface and the elevation value of the target mobile station, the elevation value of the target reference station within the same elevation datum is determined. If the two remote GNSS observation stations are not within the same elevation datum for elevation transfer, the regional elevation datum difference between the target mobile station and the target reference station is calculated based on the elevation values ​​of the target reference station and the target mobile station within the same elevation datum. Based on the elevation value of the target reference station within the same elevation datum and the regional elevation datum difference, the elevation value of the target reference station not within the same elevation datum is determined.

[0010] Optionally, in one embodiment of this application, the mathematical expression of the gravity frequency shift formula is:

[0011]

[0012] Wherein, ΔW PQ Δf represents the gravity potential difference between the two GNSS observation stations; f represents the gravity frequency shift; Δt represents the reference frequency; PQ The clock difference between the two GNSS observation stations is represented by T; standard time is represented by c; and the speed of light is represented by c.

[0013] A second aspect of this application provides an apparatus for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer, comprising: a co-location observation module for performing co-location observation using two co-location GNSS observation stations located at the same site to obtain co-location GNSS observation data of each of the two co-location GNSS observation stations; a remote comparison observation module for performing remote comparison observation using two remote GNSS observation stations located at different sites to obtain remote GNSS observation data of each of the two remote GNSS observation stations; and a time-frequency transfer module for determining gravity potential and altitude based on a preset GNSS carrier phase inter-station single-difference time-frequency transfer ... The wave phase time-frequency transfer strategy performs GNSS station-to-station single-difference processing on the co-located GNSS observation data and the remote GNSS observation data to obtain clock difference sequences during the co-located observation and remote comparison observation processes. Based on the clock difference sequences, it calculates the inherent frequency difference corresponding to the co-located observation and the remote observation frequency difference corresponding to the remote comparison observation, and calculates the gravity frequency shift corresponding to the remote comparison observation using the inherent frequency difference and the remote observation frequency difference. The calculation module is used to calculate the gravity potential difference between the two remote GNSS observation stations based on the gravity frequency shift and a preset gravity frequency shift formula, and uses the gravity potential difference to calculate the gravity potential and altitude values ​​of each remote GNSS observation station.

[0014] Optionally, in one embodiment of this application, the time-frequency transfer module includes: a first acquisition unit, configured to acquire GNSS pseudorange and carrier phase observation equations corresponding to the two remote GNSS observation stations based on the co-located GNSS observation data and the remote GNSS observation data; and a construction unit, configured to construct a GNSS inter-station single-difference carrier phase time-frequency transfer model based on the GNSS carrier phase time-frequency transfer strategy and the GNSS pseudorange and carrier phase observation equations, so as to apply the GNSS inter-station single-difference carrier phase time-frequency transfer model to the co-located GNSS observation data and the remote GNSS observation data respectively. The system performs GNSS inter-station single-difference processing to obtain clock difference sequences during co-location observation and remote comparison observation. A data processing unit processes the clock difference sequences during co-location and remote comparison observation to obtain a standard clock difference sequence. Based on the standard clock difference sequence and a preset clock difference-frequency difference conversion relationship, it calculates the inherent frequency difference during co-location observation and the remote observation frequency difference. A removal unit removes the inherent frequency difference from the remote observation frequency difference to obtain the gravity frequency shift during the remote comparison observation process between the two remote GNSS observation stations.

[0015] Optionally, in one embodiment of this application, the calculation module includes: a second acquisition unit, configured to acquire the gravity potential and altitude of the target mobile station among the two remote GNSS observation stations; a substitution unit, configured to substitute the gravity frequency shift into the gravity frequency shift formula to obtain the gravity potential difference between the two remote GNSS observation stations, and calculate the gravity potential of the target reference station based on the gravity potential difference and the gravity potential of the target mobile station; and a judgment unit, configured to determine whether the two remote GNSS observation stations are transferring elevations within the same elevation datum, and if the two remote GNSS observation stations are transferring elevations within the same elevation datum, then determine the terrain information of the area where the target mobile station and the target reference station are located, and through... The gravity potential is used to calculate the gravity equipotential surface corresponding to the terrain information; a first determining unit is used to determine the altitude of the target reference station within the same elevation datum based on the gravity equipotential surface and the altitude of the target mobile station; a difference calculation unit is used to calculate the regional elevation datum difference between the target mobile station and the target reference station based on the altitude of the target reference station and the altitude of the target mobile station within the same elevation datum if the two remote GNSS observation stations are not performing elevation transfer within the same elevation datum; a second determining unit is used to determine the altitude of the target reference station not within the same elevation datum based on the altitude of the target reference station within the same elevation datum and the regional elevation datum difference.

[0016] Optionally, in one embodiment of this application, the mathematical expression of the gravity frequency shift formula is:

[0017]

[0018] Wherein, ΔW PQ Δf represents the gravity potential difference between the two GNSS observation stations; f represents the gravity frequency shift; Δt represents the reference frequency; PQ The clock difference between the two GNSS observation stations is represented by T; standard time is represented by c; and the speed of light is represented by c.

[0019] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer as described in the above embodiments.

[0020] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer.

[0021] A fifth aspect of this application provides a computer program product, including a computer program that is executed to implement the above-described method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer.

[0022] Therefore, the embodiments of this application have the following beneficial effects:

[0023] The embodiments of this application can utilize two co-located GNSS observation stations set at the same site to perform co-located observations, thereby obtaining co-located GNSS observation data for each of the two co-located GNSS observation stations; utilize two remote GNSS observation stations set at different sites to perform remote comparison observations, thereby obtaining remote GNSS observation data for each of the two remote GNSS observation stations; based on a preset GNSS carrier phase time-frequency transfer strategy, perform GNSS inter-station single-difference processing on the co-located GNSS observation data and the remote GNSS observation data to obtain clock difference sequences during the co-located observation and remote comparison observation processes, and calculate the inherent frequency difference corresponding to the co-located observation and the remote observation frequency difference corresponding to the remote comparison observation based on the clock difference sequences, so as to calculate the gravity frequency shift corresponding to the remote comparison observation through the inherent frequency difference and the remote observation frequency difference; calculate the gravity potential difference between the two remote GNSS observation stations based on the gravity frequency shift and a preset gravity frequency shift formula, and use the gravity potential difference to calculate the gravity potential and altitude value of each remote GNSS observation station. This application utilizes GNSS carrier phase inter-station single-difference time-frequency transfer technology to achieve clock difference comparison between ground stations. Based on the principles of general relativity, it determines the gravity frequency shift between the two locations, enabling the determination of gravity potential and altitude. This eliminates the influence of satellite-end errors on GNSS time-frequency transfer, achieving high-precision clock comparison and effectively avoiding the limitations of traditional gravity potential measurement techniques. This lays the foundation for solving the problem of global elevation benchmark unification. Therefore, it solves the problems of existing technologies' inability to eliminate the influence of satellite-end errors on GNSS time-frequency transfer, their inability to overcome the limitations of traditional gravity potential measurement techniques, and their difficulty in achieving global elevation benchmark unification.

[0024] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0025] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 This is a flowchart illustrating a method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer according to an embodiment of this application.

[0027] Figure 2 A schematic diagram of gravity potential measurement using a single-difference carrier phase time-frequency transfer method between GNSS stations is provided as an embodiment of this application.

[0028] Figure 3 A schematic diagram of cross-sea elevation transfer for single-difference carrier phase transfer between GNSS stations is provided as an embodiment of this application.

[0029] Figure 4 This is an example diagram of a GNSS carrier phase inter-station single-difference time-frequency transfer device for determining gravity potential and altitude according to an embodiment of this application;

[0030] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0031] Among them, 10-GNSS carrier phase station single difference time-frequency transfer device for determining gravity potential and altitude; 100-co-site observation module, 200-remote comparison observation module, 300-time-frequency transfer module, 400-computation module; 501-memory, 502-processor, 503-communication interface. Detailed Implementation

[0032] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0033] The following describes a method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer, based on embodiments of the present application, with reference to the accompanying drawings. Addressing the problems mentioned in the background art, this application provides a method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer. In this method, co-location observations are performed using two co-located GNSS observation stations set at the same site to obtain co-location GNSS observation data for each of the two co-located GNSS observation stations; remote comparison observations are performed using two remote GNSS observation stations set at different sites to obtain remote GNSS observation data for each of the two remote GNSS observation stations; based on a preset GNSS... The S-carrier phase time-frequency transfer strategy performs inter-station single-difference processing on co-located GNSS observation data and remote GNSS observation data to obtain clock difference sequences during co-located and remote comparison observations. Based on the clock difference sequences, it calculates the inherent frequency difference corresponding to the co-located observations and the remote observation frequency difference corresponding to the remote comparison observations. It then calculates the gravity frequency shift corresponding to the remote comparison observations using the inherent frequency difference and the remote observation frequency difference. Finally, it calculates the gravity potential difference between two remote GNSS observation stations based on the gravity frequency shift and a preset gravity frequency shift formula, and uses this gravity potential difference to calculate the gravity potential and altitude values ​​of each remote GNSS observation station. This application utilizes GNSS carrier phase inter-station single-difference time-frequency transfer technology to achieve clock difference comparison between ground stations. Based on the principles of general relativity, it determines the gravity frequency shift between the two locations, realizing the determination of gravity potential and altitude. This eliminates the influence of satellite-end errors on GNSS time-frequency transfer, achieving high-precision clock comparison and effectively avoiding the limitations of traditional gravity potential measurement techniques, laying the foundation for solving the problem of global elevation benchmark unification. This solves the problems that existing technologies cannot eliminate the impact of satellite-end errors on GNSS time and frequency transmission, cannot overcome the limitations of traditional gravity potential measurement technology, and cannot achieve a unified global elevation benchmark.

[0034] Specifically, Figure 1 This is a flowchart illustrating a method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer, as provided in an embodiment of this application.

[0035] like Figure 1 As shown, the method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer includes the following steps:

[0036] In step S101, co-location observation is performed using two co-location GNSS observation stations located at the same site to obtain co-location GNSS observation data for each of the two co-location GNSS observation stations.

[0037] In step S102, remote comparison observations are performed using two remote GNSS observation stations set at different sites to obtain remote GNSS observation data for each of the two remote GNSS observation stations.

[0038] In practical implementation, embodiments of this application can place two sets of instruments at point P (i.e., the target reference station) to establish two co-located GNSS observation stations and obtain corresponding co-located GNSS observation data. Each set of instruments includes a high-performance clock (hydrogen atom clock or optical clock), a GNSS time and frequency receiver, a GNSS antenna, GNSS cables, and environmental control equipment (to maintain a suitable and stable operating environment for the clock). Co-located observations by the two sets of instruments at the same station enable the calibration of two clocks.

[0039] After a period of observation at the same location, in this embodiment of the application, one set of instruments can be transported to point Q (i.e., the target mobile station) to establish a new GNSS observation station (i.e., two remote GNSS observation stations). At this time, the observation stations at points P and Q conduct remote synchronous observations to obtain the corresponding remote GNSS observation data.

[0040] In step S103, based on the preset GNSS carrier phase time-frequency transfer strategy, the co-located GNSS observation data and the remote GNSS observation data are subjected to GNSS inter-station single difference processing to obtain the clock difference sequence in the co-located observation and remote comparison observation process. The inherent frequency difference corresponding to the co-located observation and the remote observation frequency difference corresponding to the remote comparison observation are calculated according to the clock difference sequence, so as to calculate the gravity frequency shift corresponding to the remote comparison observation through the inherent frequency difference and the remote observation frequency difference.

[0041] Those skilled in the art should understand that in recent years, with the rapid development of Global Navigation Satellite Systems (GNSS), GNSS time and frequency transfer technology has become increasingly mature, bringing new opportunities for gravity potential observation. On the one hand, GNSS satellites can transfer time and frequency, a capability that gives them the potential to directly measure gravity potential; on the other hand, GNSS satellites are numerous, have extremely low observation costs, possess all-weather observation capabilities, and offer extremely wide coverage, largely unaffected by baseline length limitations. Furthermore, with the International GNSS Service (IGS) providing high-precision satellite orbit and clock error products, and the improvement of various error correction models, the accuracy of GNSS carrier phase time and frequency transfer can reach sub-nanosecond levels, and the stability can reach 10⁻⁶. -17 This presents new opportunities for the global implementation of time-frequency signal measurement of gravity potential.

[0042] GNSS time-frequency transfer techniques mainly include common-view time transfer, full-view time transfer, and GNSS carrier phase time-frequency transfer. The GNSS carrier phase time-frequency transfer method can be further subdivided into GNSS single-point carrier phase time-frequency transfer and GNSS inter-station single-difference carrier phase time-frequency transfer. Both the full-view and common-view time transfer methods only use pseudorange observations, and due to the noise of these pseudorange observations, their accuracy cannot be significantly improved. Considering that the accuracy of carrier phase observations is two orders of magnitude higher than that of pseudorange observations, a time transfer method extending from the full-view method, using carrier phase observations for time-frequency transfer, is called GNSS single-point carrier phase time-frequency transfer. This method not only retains the characteristic of the full-view time transfer method being unrestricted by baseline length but also utilizes the high accuracy of carrier phase observations. The GNSS inter-station single-difference carrier phase time-frequency transfer technique uses the same observations as the GNSS single-point carrier phase time-frequency transfer technique. The difference lies in that the GNSS inter-station single-difference carrier phase time-frequency transfer technique differentially analyzes the signals from the same satellite observed by two receivers. This effectively reduces the impact of satellite clock errors, orbital errors, and ionospheric errors on the time-frequency transfer results, especially in short-baseline measurements, where these errors are highly correlated over short distances, and differential analysis significantly weakens their influence. Therefore, using the GNSS inter-station single-difference carrier phase time-frequency transfer technique for gravity potential determination has significant advantages.

[0043] Understandably, research on GNSS inter-station single-difference carrier phase time-frequency transfer for determining gravity potential and altitude will open up new methods for gravity potential measurement, expand the application of GNSS satellites to the direct observation of gravity potential and altitude, solve the problem of unifying global elevation benchmarks, promote the development of fundamental physics in my country, enhance the level of time-frequency science and technology in my country, and advance the interdisciplinary integration of multiple disciplines. This technology is expected to be widely used in earth sciences, space sciences, physics, environmental monitoring, and national infrastructure construction, and has significant scientific and strategic importance.

[0044] Therefore, embodiments of this application can use a high-performance atomic clock as the reference clock for a GNSS receiver, providing the GNSS receiver with a high-precision and high-stability time and frequency reference, enabling high-precision GNSS observations, and directly calculating the clock difference between two GNSS stations using GNSS inter-station single-difference carrier phase time-frequency transfer technology, thereby extracting gravity frequency shift information between the two stations.

[0045] Optionally, in one embodiment of this application, based on a preset GNSS carrier phase time-frequency transfer strategy, GNSS inter-station single-difference processing is performed on co-located GNSS observation data and remote GNSS observation data to obtain clock difference sequences during co-located observation and remote comparison observation. The inherent frequency difference corresponding to the co-located observation and the remote observation frequency difference corresponding to the remote comparison observation are calculated based on the clock difference sequences. The gravity frequency shift corresponding to the remote comparison observation is then calculated using the inherent frequency difference and the remote observation frequency difference. This includes: obtaining GNSS pseudorange and carrier phase observation equations corresponding to two remote GNSS observation stations based on the co-located GNSS observation data and the remote GNSS observation data; and using the GNSS carrier phase time-frequency transfer strategy and GNSS pseudorange and carrier phase... An inter-station single-difference carrier phase time-frequency transfer model is constructed using the observation equations. This model is used to perform inter-station single-difference processing on both co-located and remote GNSS observation data to obtain clock bias sequences during co-located and remote comparison observations. Data processing is then performed on these clock bias sequences to obtain a standard clock bias sequence. Based on the standard clock bias sequence and a predefined clock bias-frequency difference conversion relationship, the inherent frequency difference during co-located observations and the remote observation frequency difference are calculated. The inherent frequency difference in the remote observation frequency difference is then removed to obtain the gravity frequency shift during the remote comparison observation process between the two remote GNSS observation stations.

[0046] As one possible approach, after the observation is completed, the embodiments of this application can perform GNSS inter-station single-difference carrier phase time-frequency transfer model on the data of co-site observation and remote observation, directly calculate the clock difference sequence between the two clocks during the co-site observation and remote observation process (i.e., between the rover station and the reference station), and perform a series of post-processing (denoising, period removal, etc.) on the two sets of clock difference sequences to obtain the processed clock difference sequence (i.e., the standard clock difference sequence).

[0047] If both the rover and the reference station are equipped with high-performance clocks (such as hydrogen atomic clocks, optical clocks, etc.), the gravity frequency shift information between the rover and the reference station can be extracted by calculating the clock difference. Specifically, in the embodiments of this application, the processed clock difference sequence can be converted into the corresponding frequency difference according to the conversion relationship between clock difference and frequency difference, and the inherent frequency difference of the two clocks during co-location observation and the frequency difference of the two clocks during remote observation can be obtained. By removing the inherent frequency difference of the two clocks from the frequency difference measured during remote observation, the gravity frequency shift of the two clocks during remote observation can be obtained.

[0048] The following describes and introduces the GNSS carrier phase time-frequency transfer strategy involved in the embodiments of this application.

[0049] In the embodiments of this application, the complete observation equations for GNSS pseudorange and carrier phase can be expressed as follows:

[0050]

[0051] Where P is the pseudorange observation (unit: m); L is the carrier phase observation (unit: cycle); the superscript S indicates the satellite system (e.g., GPS / GLONASS / Galileo / BDS / QZSS); the superscript i indicates the satellite's PRN (Pseudo-Random Noise); the subscripts r and j represent the frequency identifiers of the station receiver and the observation, respectively; λ j Represents frequency f j The corresponding carrier wavelength (unit: m); ρ represents the geometric distance between the satellite and the station (unit: m); dt r With dt s These represent the clock difference between the receiver and the satellite (unit: seconds). Z represents the wetted delay projection function (MF) related to the satellite elevation angle; w，r The zenith wet delay (ZWD) of the station is represented by m; γ represents the frequency-dependent ionospheric delay amplification factor. The spherical delay corresponding to frequency f1 (unit: m) is represented. and These represent the uncalibrated pseudorange hardware delay (UCD) at the receiver end and the satellite end, respectively (unit: m). Indicates carrier phase ambiguity; and ζ and ξ represent the uncalibrated phase delay (UPD) at the receiver and satellite ends, respectively (unit: cycles); ζ and ξ represent the sum of noise, multipath effects, and other unmodeled errors in pseudorange and phase observations, respectively (unit: meters). Furthermore, other errors in the GNSS observation equations, such as the phase center error between the satellite and antenna, tropospheric dry delay (Zenith Hydrostatic Delay (ZHD)), relativistic elliptical orbit effects, Shapiro effect, solid tides, polar tides, and ocean tidal load deformation, Sagnac effect, and phase wind-up (PhWU) of the satellite antenna, have all been corrected in advance through the model.

[0052] For ease of description, the following expression is defined:

[0053]

[0054] Here, subscripts 1 and 2 represent frequency identifiers. and These are the coefficients of the dual-frequency signal combination; and These are the differential code biases (DCB) between frequency 1 and frequency 2 at the satellite and receiver ends, respectively. To eliminate the pseudorange hardware delay at the satellite end after ionospheric combination.

[0055] The precise satellite orbit and clock bias products provided by the IGS Analysis Center are estimated based on combined observations of dual-frequency pseudorange ionosphere-free (IF) data (e.g., GPS: L1 / L2, GLONASS: G1 / G2, BDS: B1I / B3I, and Galileo: E1 / E5a). These products include the hardware delay of the satellite-end pseudorange dual-frequency ionosphere-free combination, i.e.:

[0056]

[0057] in, Precision satellite clock bias provided for IGS; dD is the deviation of the satellite clock product reference standard (unit: m), which is consistent for all satellites within the same system; To eliminate the pseudorange hardware delay at the satellite end after ionospheric integration. Because GLONASS uses an FDMA signal modulation structure, its observations also contain inter-frequency phase bias (IFPB) and inter-frequency code bias (IFCB). IFPB can be absorbed by ambiguity parameters (and is negligible during floating-point data processing). The GLONASS receiver end... Including frequency-independent components and frequency-related parts It can be represented as:

[0058]

[0059] After using satellite precision orbit, clock bias, and DCB products, and linearizing equation (1), we get:

[0060]

[0061] in,

[0062]

[0063] Where p and l represent the observed values ​​of pseudorange and carrier phase minus the calculated values ​​(Observed Minus Computed, OMC), respectively; The direction cosine; This represents the coordinate increment relative to the receiver's initial coordinates; the superscript symbol "~" indicates a parameter that has been reparameterized.

[0064] To eliminate the influence of the first-order term of ionospheric delay, the GNSS inter-station single-difference carrier phase time-frequency transfer technology typically uses dual-frequency pseudorange and dual-frequency carrier phase observations to construct an ionospheric-free combined model, obtaining the ionospheric-free combined observation equations for pseudorange and carrier phase. Then, by simultaneously solving all the observation equations, the three-dimensional coordinates of the station and the receiver clock error can be obtained.

[0065]

[0066] in,

[0067]

[0068] In this model, the subscripts 1 and 2 in the subscript IF represent the frequencies used in the dual-frequency de-ionization combination. The parameters to be estimated in this model include: the increment of the receiver's three-dimensional coordinates, the receiver's clock bias, ZWD, and the ambiguity of the dual-frequency de-ionization combination, and at least 5 satellites need to be observed for the calculation to be performed.

[0069] When performing single-difference carrier phase time-frequency transfer between multi-mode GNSS combined stations, the clock bias references of each satellite system are not consistent, requiring unification of the clock biases of each satellite system to a common time reference. Taking the unified conversion to the GPS time reference as an example, the receiver clock biases of GLONASS, BDS, and Galileo, which reference the time of each system, are unified to the receiver clock bias referenced to GPS Time (GPST), and the inter-system bias (ISB) between each GNSS system needs to be estimated additionally. At this point, the model for non-differenced PPP time-frequency transfer of GPS, GLONASS, BDS, and Galileo multi-system dual-frequency de-ionization combined systems can be expressed as:

[0070]

[0071] in,

[0072]

[0073] in, and These represent the ISB (unit: m) between GLONASS, BDS, Galileo, and GPS, respectively. It should be noted that in this embodiment of the application, BDS-2 and BDS-3 are treated as two separate systems when performing combined data processing of BDS-2 and BDS-3.

[0074] Based on equation (1), assuming that the base station (subscript b) and the rover station (subscript r) simultaneously observe satellite i, the inter-station single-difference carrier phase time-frequency transfer observations can be composed of differences between the stations. The inter-station single-difference method eliminates satellite-related errors while preserving receiver clock bias parameters, and can be used as a time-frequency transfer method. Considering that the coordinates of the base station are known, the linearized inter-station single-difference dual-frequency de-ionospheric combined time-frequency transfer model can be expressed as:

[0075]

[0076] in,

[0077]

[0078] Where Δ is the single difference factor, defined as Δ(·) rb =(·) b -(·) r The inter-station single-difference carrier phase time-frequency transfer model eliminates and weakens the effects of orbital errors, satellite clock error residuals, and atmospheric delays on short baselines.

[0079] Because additional estimation of the single-difference ISB parameter is required, using GPS clock bias as a benchmark, the combined single-difference time-frequency transfer model for the GPS, GLONASS, BDS, and Galileo multi-system dual-frequency de-ionization combination is as follows:

[0080]

[0081] in,

[0082]

[0083] Since the baseline of time and frequency transfer is generally long, the elevation angles of the same satellite observed by the base station (i.e., the reference station) and the rover station (i.e., the mobile station) may differ significantly, resulting in inconsistent projection functions of the tropospheric ZWD between the two stations. Therefore, the model needs to estimate the ZWD parameters of both the base station and the rover station simultaneously.

[0084] Therefore, the embodiments of this application analyze the GNSS carrier phase inter-station single-difference time-frequency transfer model to perform GNSS data calculation based on the GNSS carrier phase inter-station single-difference time-frequency transfer model, thereby directly obtaining the clock difference sequence between the two stations.

[0085] In step S104, the gravity potential difference between two remote GNSS observation stations is calculated based on the gravity frequency shift and a preset gravity frequency shift formula, and the gravity potential and altitude value of each remote GNSS observation station are calculated using the gravity potential difference.

[0086] Furthermore, embodiments of this application can calculate the gravitational potential difference between points P and Q using the gravity frequency shift formula. Assuming the gravitational potential of point P is known, the gravitational potential of point Q can be determined. If the altitude of point P is known, the altitude of point Q can be determined. If points P and Q are located on two different landmasses, cross-sea elevation transfer can be achieved. If points P and Q are elevation benchmarks for two different landmasses, unification between the two elevation benchmarks can be achieved.

[0087] Therefore, the embodiments of this application determine the gravity potential difference between two stations based on the gravity frequency shift formula, thereby enabling cross-sea elevation measurement and potentially solving the problem of unifying global elevation benchmarks.

[0088] Optionally, in one embodiment of this application, the gravity potential difference between two remote GNSS observation stations is calculated based on gravity frequency shift and a preset gravity frequency shift formula, and the gravity potential and altitude values ​​of each remote GNSS observation station are calculated using the gravity potential difference. This includes: obtaining the gravity potential and altitude value of the target mobile station of the target mobile station among the two remote GNSS observation stations; substituting the gravity frequency shift into the gravity frequency shift formula to obtain the gravity potential difference between the two remote GNSS observation stations, and calculating the gravity potential of the target reference station based on the gravity potential difference and the gravity potential of the target mobile station; determining whether the two remote GNSS observation stations are performing elevation transfer within the same elevation datum, and if the two remote GNSS observation stations are within the same elevation datum... If elevation transfer is performed within the same elevation datum, the topographic information of the areas where the target mobile station and the target reference station are located is determined, and the gravity equipotential surface corresponding to the topographic information is calculated using gravity potential. Based on the gravity equipotential surface and the elevation value of the target mobile station, the elevation value of the target reference station within the same elevation datum is determined. If elevation transfer is performed between two remote GNSS observation stations that are not within the same elevation datum, the regional elevation datum difference between the target mobile station and the target reference station is calculated based on the elevation values ​​of the target reference station and the target mobile station within the same elevation datum. Based on the elevation value of the target reference station within the same elevation datum and the regional elevation datum difference, the elevation value of the target reference station that is not within the same elevation datum is determined.

[0089] Furthermore, in the embodiments of this application, the gravitational potential difference between two stations can be determined according to the general relativistic gravity frequency shift formula.

[0090] Optionally, in one embodiment of this application, the mathematical expression of the gravity frequency shift formula is:

[0091]

[0092] Wherein, ΔW PQ Δf represents the gravity potential difference between two GNSS observation stations; f represents the gravity frequency shift; Δt represents the reference frequency; PO This represents the clock difference between two GNSS observation stations; T represents standard time; and c represents the speed of light.

[0093] It should be noted that the gravity frequency shift formula in the embodiments of this application is as follows:

[0094]

[0095] Wherein, ΔW PQ =W Q -W P Δf is the gravitational potential difference between rover station P and reference station Q; Δf is the gravitational frequency shift between the rover's clock and the reference station's clock; f is the standard frequency; T is the standard time; Δt PQ =t Q -t P Let c be the clock difference between stations P and Q, and c be the speed of light. Figure 2 As shown, when the gravity potential of the reference station is known, the gravity potential of the rover's location can be determined according to equation (15), thus realizing the determination of the gravity potential of the remote station.

[0096] Specifically, assuming elevation transfer occurs between ground points P and Q, the gravity equipotential surface at point P is W. P If it is unfolded at the geoid W0, then W P It can be represented as:

[0097]

[0098] in, The gravity value of the projection of point P onto the geoid (unit: m) 2 / s 2 ), H P The positive elevation of point P (unit: m).

[0099] When the measuring station is located in a plain or relatively flat area, this embodiment only considers the first-order term of equation (16). In this case, the elevation of point P can be expressed as:

[0100]

[0101] in, Let this be the average gravity value along the vertical line at point P. When the elevation is low, the gravity value at point P can be used instead. Alternatively, a more rigorous shallow-surface method can be used, which involves calculating the average gravity value along the vertical line passing through point P.

[0102] Similarly, the elevation of ground point Q can be expressed as:

[0103]

[0104] in, Let be the average gravity at point Q along the vertical line.

[0105] If the gravitational force g at points P and Q on the ground at altitude H is... P and g Q Given (unit: gal), then the mean gravity It can be approximated as:

[0106]

[0107] Combining equations (17)-(19), the elevation H of ground point Q can be obtained. Q for:

[0108]

[0109] When the measuring station is located in a mountainous area or where there is a significant elevation difference between two locations, the influence of higher-order terms also needs to be considered. The gravity equipotential surface W at ground point P is... P Using integral form, it can be precisely expressed as:

[0110]

[0111] Where P′ is the projection of point P onto the geoid. Expanding equation (21) to the second order, we obtain its practical calculation formula:

[0112]

[0113] in, R is the Earth's radius (unit: m); Equation (22) can be expressed as:

[0114]

[0115] Similarly, the gravitational equipotential surface W where point Q on the ground is located... Q It can be represented as:

[0116]

[0117] By combining equations (23) and (24), the elevation H of ground point Q can be obtained. Q Approximately:

[0118]

[0119] It should be noted that equations (20) and (25) are only applicable to elevation transfer within the same elevation datum. If elevation transfer is performed between two different elevation datums (such as the Chinese elevation datum and the North American elevation datum), the system differences between the two datums must also be considered, such as... Figure 3 As shown.

[0120] Among them, the difference between regional elevation datum and global elevation datum It can be represented as:

[0121]

[0122] in, W0 and W0 represent the gravity potential of the regional elevation datum and the global elevation datum, respectively. The average gravity of the regional elevation benchmark.

[0123] According to equations (17) and (18), if the elevation datums of the areas where ground points P and Q are located are different, then the difference between the elevation datums of the two locations is... It can be represented as:

[0124]

[0125] in, and These are the gravity potentials of the elevation datum surface in the areas where ground points P and Q are located, respectively; and Let H be the average gravity of the elevation benchmark points in the areas where P and Q are located. Then, by combining equations (25) and (27), the elevation H of ground point Q can be obtained. Q for:

[0126]

[0127] From equations (20), (25), and (28), it can be seen that if the gravitational potential and altitude of point P are precisely known, then the altitude of point Q can be determined, and the accuracy of the altitude of point Q mainly depends on the gravitational potential difference ΔW. PQ The accuracy.

[0128] In summary, the embodiments of this application utilize GNSS carrier phase inter-station single-difference time-frequency transfer technology to achieve clock difference comparison between ground stations, and based on the principles of general relativity, determine the gravity frequency shift between the two locations, thereby achieving the determination of gravity potential and altitude. Thus, this application can eliminate the influence of satellite-end errors on GNSS time-frequency transfer to achieve high-precision clock comparison, effectively avoiding the limitations of traditional gravity potential measurement techniques (combined leveling and gravity measurements). Simultaneously, this application provides a feasible solution for achieving global elevation benchmark unification, laying the foundation for solving the problem of global elevation benchmark unification.

[0129] The method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer proposed in this application involves: performing co-located observations using two co-located GNSS observation stations at the same site to obtain co-located GNSS observation data for each of the two co-located GNSS observation stations; performing remote comparison observations using two remote GNSS observation stations at different sites to obtain remote GNSS observation data for each of the two remote GNSS observation stations; and using a preset GNSS carrier phase time-frequency transfer... The strategy involves performing inter-station single-difference processing on both co-located and remote GNSS observation data to obtain clock difference sequences during co-located and remote comparison observations. Based on these clock difference sequences, the inherent frequency difference corresponding to the co-located observations and the remote observation frequency difference corresponding to the remote comparison observations are calculated. The gravity frequency shift corresponding to the remote comparison observations is then calculated using these inherent and remote observation frequency differences. The gravity potential difference between the two remote GNSS observation stations is calculated based on the gravity frequency shift and a pre-defined gravity frequency shift formula. Finally, the gravity potential and altitude values ​​of each remote GNSS observation station are calculated using the gravity potential difference. This application utilizes GNSS carrier phase inter-station single-difference time-frequency transfer technology to achieve clock difference comparison between ground stations. Based on the principles of general relativity, the gravity frequency shift between the two locations is determined, enabling the measurement of gravity potential and altitude. This eliminates the influence of satellite-end errors on GNSS time-frequency transfer, achieving high-precision clock comparison and effectively avoiding the limitations of traditional gravity potential measurement techniques. This lays the foundation for solving the problem of global elevation benchmark unification.

[0130] Secondly, with reference to the accompanying drawings, an apparatus for determining gravity potential and altitude based on the embodiments of this application using GNSS carrier phase inter-station single-difference time-frequency transfer is described.

[0131] Figure 4 This is a block diagram of a GNSS carrier phase inter-station single-difference time-frequency transfer device for measuring gravity potential and altitude according to an embodiment of this application.

[0132] like Figure 4 As shown, the device 10 for determining gravity potential and altitude by single-difference time-frequency transfer between GNSS carrier phase stations includes: a co-location observation module 100, a remote comparison observation module 200, a time-frequency transfer module 300, and a calculation module 400.

[0133] The co-location observation module 100 is used to perform co-location observation using two co-location GNSS observation stations set at the same site, so as to obtain co-location GNSS observation data of each of the two co-location GNSS observation stations.

[0134] The remote comparison observation module 200 is used to perform remote comparison observations using two remote GNSS observation stations set at different sites, so as to obtain remote GNSS observation data of each of the two remote GNSS observation stations.

[0135] The time-frequency transfer module 300 is used to perform GNSS inter-station single-difference processing on co-located GNSS observation data and remote GNSS observation data based on a preset GNSS carrier phase time-frequency transfer strategy, so as to obtain the clock difference sequence in the co-located observation and remote comparison observation process, and calculate the inherent frequency difference corresponding to the co-located observation and the remote observation frequency difference corresponding to the remote comparison observation based on the clock difference sequence, so as to calculate the gravity frequency shift corresponding to the remote comparison observation through the inherent frequency difference and the remote observation frequency difference.

[0136] The calculation module 400 is used to calculate the gravity potential difference between two remote GNSS observation stations based on the gravity frequency shift and a preset gravity frequency shift formula, and to use the gravity potential difference to calculate the gravity potential and altitude value of each remote GNSS observation station.

[0137] Optionally, in one embodiment of this application, the time-frequency transfer module 300 includes: a first acquisition unit, a construction unit, a data processing unit, and a rejection unit.

[0138] The first acquisition unit is used to acquire the GNSS pseudorange and carrier phase observation equations corresponding to two remote GNSS observation stations based on co-located GNSS observation data and remote GNSS observation data.

[0139] The construction unit is used to build a GNSS inter-station single-difference carrier phase time-frequency transfer model based on the GNSS carrier phase time-frequency transfer strategy and the GNSS pseudorange and carrier phase observation equations. The GNSS inter-station single-difference carrier phase time-frequency transfer model is used to perform GNSS inter-station single-difference processing on co-located GNSS observation data and remote GNSS observation data respectively, so as to obtain the clock difference sequence in the co-located observation process and the clock difference sequence in the remote comparison observation process.

[0140] The data processing unit is used to process the clock difference sequence in the co-location observation process and the clock difference sequence in the remote comparison observation process to obtain the standard clock difference sequence, and to calculate the inherent frequency difference in the co-location observation process and the remote observation frequency difference based on the standard clock difference sequence and the preset clock difference-frequency difference conversion relationship.

[0141] The elimination unit is used to eliminate the inherent frequency difference in the remote observation frequency difference in order to obtain the gravity frequency shift during the remote comparison observation process between two remote GNSS observation stations.

[0142] Optionally, in one embodiment of this application, the calculation module 400 includes: a second acquisition unit, a substitution unit, a judgment unit, a first determination unit, a difference calculation unit, and a second determination unit.

[0143] The second acquisition unit is used to acquire the target rover station's gravity potential and altitude value between the two remote GNSS observation stations.

[0144] The substitution unit is used to substitute the gravity frequency shift into the gravity frequency shift formula to obtain the gravity potential difference between two remote GNSS observation stations, and to calculate the gravity potential of the target reference station based on the gravity potential difference and the gravity potential of the target mobile station.

[0145] The judgment unit is used to determine whether two remote GNSS observation stations are transferring elevations within the same elevation datum. If the two remote GNSS observation stations are transferring elevations within the same elevation datum, the terrain information of the area where the target mobile station and the target reference station are located is determined, and the gravity equipotential surface corresponding to the terrain information is calculated through gravity potential.

[0146] The first determining unit is used to determine the target reference station elevation value within the same elevation datum based on the gravity equipotential surface and the target flow station elevation value.

[0147] The difference calculation unit is used to calculate the regional elevation datum difference between the target mobile station and the target reference station if the elevation transfer between two remote GNSS observation stations is not within the same elevation datum. This is based on the elevation height of the target reference station and the elevation height of the target mobile station within the same elevation datum.

[0148] The second determining unit is used to determine the elevation values ​​of target reference stations that are not within the same elevation datum, based on the elevation values ​​of target reference stations within the same elevation datum and the regional elevation datum differences.

[0149] Optionally, in one embodiment of this application, the mathematical expression of the gravity frequency shift formula is:

[0150]

[0151] Wherein, ΔW PQ Δf represents the gravity potential difference between two GNSS observation stations; f represents the gravity frequency shift; Δt represents the reference frequency; PQ This represents the clock difference between two GNSS observation stations; T represents standard time; and c represents the speed of light.

[0152] It should be noted that the explanation of the above-described method embodiment for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer also applies to the device for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer in this embodiment, and will not be repeated here.

[0153] The apparatus for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer according to the embodiments of this application includes a co-site observation module for performing co-site observation using two co-site GNSS observation stations located at the same site to obtain co-site GNSS observation data of each of the two co-site GNSS observation stations; a remote comparison observation module for performing remote comparison observation using two remote GNSS observation stations located at different sites to obtain remote GNSS observation data of each of the two remote GNSS observation stations; and a time-frequency transfer module for determining gravity potential and altitude based on a preset time-frequency transfer ... This application employs a GNSS carrier phase time-frequency transfer strategy, performing inter-station single-difference processing on co-located and remote GNSS observation data to obtain clock difference sequences during co-located and remote comparison observations. Based on these clock difference sequences, it calculates the inherent frequency difference corresponding to the co-located observations and the remote observation frequency difference corresponding to the remote comparison observations. This allows for the calculation of the gravity frequency shift corresponding to the remote comparison observations using the inherent and remote observation frequency differences. A calculation module is used to calculate the gravity potential difference between two remote GNSS observation stations based on the gravity frequency shift and a preset gravity frequency shift formula. This gravity potential difference is then used to calculate the gravity potential and altitude values ​​for each remote GNSS observation station. This application utilizes GNSS carrier phase inter-station single-difference time-frequency transfer technology to achieve clock difference comparison between ground stations. Based on the principles of general relativity, it determines the gravity frequency shift between the two locations, enabling the determination of gravity potential and altitude. This eliminates the influence of satellite-end errors on GNSS time-frequency transfer, achieving high-precision clock comparison and effectively avoiding the limitations of traditional gravity potential measurement techniques. This lays the foundation for solving the problem of global elevation benchmark unification.

[0154] Figure 5 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:

[0155] The memory 501, the processor 502, and the computer program stored on the memory 501 and capable of running on the processor 502.

[0156] When the processor 502 executes the program, it implements the method for determining gravity potential and altitude by GNSS carrier phase inter-station single-difference time-frequency transfer provided in the above embodiments.

[0157] Furthermore, electronic devices also include:

[0158] Communication interface 503 is used for communication between memory 501 and processor 502.

[0159] The memory 501 is used to store computer programs that can run on the processor 502.

[0160] The memory 501 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0161] If the memory 501, processor 502, and communication interface 503 are implemented independently, then the communication interface 503, memory 501, and processor 502 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, Figure 5 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0162] Optionally, in a specific implementation, if the memory 501, processor 502, and communication interface 503 are integrated on a single chip, then the memory 501, processor 502, and communication interface 503 can communicate with each other through an internal interface.

[0163] Processor 502 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0164] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer.

[0165] This application also provides a computer program product, including a computer program, which, when executed, is used to implement the above-described method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer.

[0166] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0167] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0168] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0169] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0170] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0171] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0172] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0173] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer, characterized in that, Includes the following steps: Co-location observations are conducted using two co-location GNSS observation stations located at the same site to obtain co-location GNSS observation data for each of the two co-location GNSS observation stations. Remote comparison observations are conducted using two remote GNSS observation stations located at different sites to obtain remote GNSS observation data for each of the two remote GNSS observation stations. Based on a preset GNSS carrier phase time-frequency transfer strategy, the co-located GNSS observation data and the remote GNSS observation data are subjected to GNSS inter-station single-difference processing to obtain clock difference sequences in the co-located observation and remote comparison observation processes. The inherent frequency difference corresponding to the co-located observation and the remote observation frequency difference corresponding to the remote comparison observation are calculated based on the clock difference sequences. The gravity frequency shift corresponding to the remote comparison observation is then calculated using the inherent frequency difference and the remote observation frequency difference. The gravity potential difference between the two remote GNSS observation stations is calculated based on the gravity frequency shift and a preset gravity frequency shift formula, and the gravity potential and altitude value of each remote GNSS observation station are calculated using the gravity potential difference.

2. The method according to claim 1, characterized in that, The method based on a preset GNSS carrier phase time-frequency transfer strategy performs GNSS inter-station single-difference processing on the co-located GNSS observation data and the remote GNSS observation data to obtain clock difference sequences during co-located and remote comparison observations. It then calculates the inherent frequency difference corresponding to the co-located observations and the remote observation frequency difference corresponding to the remote comparison observations based on the clock difference sequences. Finally, it calculates the gravity frequency shift corresponding to the remote comparison observations using the inherent frequency difference and the remote observation frequency difference. Based on the co-located GNSS observation data and the remote GNSS observation data, obtain the GNSS pseudorange and carrier phase observation equations corresponding to the two remote GNSS observation stations; Based on the GNSS carrier phase time-frequency transfer strategy and the GNSS pseudorange and carrier phase observation equations, a GNSS inter-station single-difference carrier phase time-frequency transfer model is constructed. The GNSS inter-station single-difference carrier phase time-frequency transfer model is used to perform GNSS inter-station single-difference processing on the co-located GNSS observation data and the remote GNSS observation data, respectively, to obtain the clock difference sequence in the co-located observation process and the clock difference sequence in the remote comparison observation process. The clock difference sequences in the co-location observation process and the remote comparison observation process are processed to obtain a standard clock difference sequence. Based on the standard clock difference sequence and a preset clock difference-frequency difference conversion relationship, the inherent frequency difference in the co-location observation process and the remote observation frequency difference are calculated. The inherent frequency difference in the remote observation frequency difference is removed to obtain the gravity frequency shift during the remote comparison observation process of the two remote GNSS observation stations.

3. The method according to claim 2, characterized in that, The step of calculating the gravity potential difference between the two remote GNSS observation stations based on the gravity frequency shift and a preset gravity frequency shift formula, and using the gravity potential difference to calculate the gravity potential and altitude values ​​of each remote GNSS observation station, includes: Obtain the target rover station's gravity potential and altitude value from the two remote GNSS observation stations; Substitute the gravity frequency shift into the gravity frequency shift formula to obtain the gravity potential difference between the two remote GNSS observation stations, and calculate the gravity potential of the target reference station based on the gravity potential difference and the gravity potential of the target mobile station. Determine whether the two remote GNSS observation stations are transferring elevations within the same elevation datum. If the two remote GNSS observation stations are transferring elevations within the same elevation datum, determine the terrain information of the area where the target mobile station and the target reference station are located, and calculate the gravity equipotential surface corresponding to the terrain information using the gravity potential. The target reference station elevation value within the same elevation datum is determined based on the gravity equipotential surface and the elevation value of the target mobile station. If the two remote GNSS observation stations do not transfer elevation within the same elevation datum, then the regional elevation datum difference between the target mobile station and the target reference station is calculated based on the elevation height of the target reference station and the elevation height of the target mobile station within the same elevation datum. The elevation values ​​of target reference stations not located within the same elevation datum are determined based on the elevation values ​​of the target reference stations within the same elevation datum and the differences between the regional elevation datums.

4. The method according to claim 3, characterized in that, The mathematical expression for the gravity frequency shift formula is: Wherein, ΔW PQ Δf represents the gravity potential difference between the two GNSS observation stations; f represents the gravity frequency shift; Δt represents the reference frequency; PQ The clock difference between the two GNSS observation stations is represented by T; standard time is represented by c; and the speed of light is represented by c.

5. A device for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer, characterized in that, include: The co-location observation module is used to perform co-location observation using two co-location GNSS observation stations set at the same site, so as to obtain the co-location GNSS observation data of each of the two co-location GNSS observation stations. The remote comparison observation module is used to perform remote comparison observation using two remote GNSS observation stations set at different sites, so as to obtain the remote GNSS observation data of each of the two remote GNSS observation stations. The time-frequency transfer module is used to perform GNSS inter-station single-difference processing on the co-located GNSS observation data and the remote GNSS observation data based on a preset GNSS carrier phase time-frequency transfer strategy, so as to obtain the clock difference sequence in the co-located observation and remote comparison observation process, and calculate the inherent frequency difference corresponding to the co-located observation and the remote observation frequency difference corresponding to the remote comparison observation based on the clock difference sequence, so as to calculate the gravity frequency shift corresponding to the remote comparison observation through the inherent frequency difference and the remote observation frequency difference; The calculation module is used to calculate the gravity potential difference between the two remote GNSS observation stations based on the gravity frequency shift and a preset gravity frequency shift formula, and to use the gravity potential difference to calculate the gravity potential and altitude value of each remote GNSS observation station.

6. The apparatus according to claim 5, characterized in that, The time-frequency transfer module includes: The first acquisition unit is used to acquire the GNSS pseudorange and carrier phase observation equations corresponding to the two remote GNSS observation stations based on the co-located GNSS observation data and the remote GNSS observation data. The construction unit is used to construct a GNSS inter-station single-difference carrier phase time-frequency transfer model based on the GNSS carrier phase time-frequency transfer strategy and the GNSS pseudorange and carrier phase observation equations. The GNSS inter-station single-difference carrier phase time-frequency transfer model is used to perform GNSS inter-station single-difference processing on the co-located GNSS observation data and the remote GNSS observation data respectively to obtain the clock difference sequence in the co-located observation process and the clock difference sequence in the remote comparison observation process. The data processing unit is used to process the clock difference sequence in the co-location observation process and the clock difference sequence in the remote comparison observation process to obtain a standard clock difference sequence, and to calculate the inherent frequency difference in the co-location observation process and the remote observation frequency difference based on the standard clock difference sequence and a preset clock difference-frequency difference conversion relationship. The elimination unit is used to eliminate the inherent frequency difference in the remote observation frequency difference to obtain the gravity frequency shift during the remote comparison observation process of the two remote GNSS observation stations.

7. The apparatus according to claim 6, characterized in that, The computing module includes: The second acquisition unit is used to acquire the target mobile station gravity potential and target mobile station altitude value of the target mobile station among the two remote GNSS observation stations. The substitution unit is used to substitute the gravity frequency shift into the gravity frequency shift formula to obtain the gravity potential difference between the two remote GNSS observation stations, and to calculate the gravity potential of the target reference station based on the gravity potential difference and the gravity potential of the target mobile station. The judgment unit is used to determine whether the two remote GNSS observation stations are transferring elevations within the same elevation datum. If the two remote GNSS observation stations are transferring elevations within the same elevation datum, the terrain information of the area where the target mobile station and the target reference station are located is determined, and the gravity isopotential surface corresponding to the terrain information is calculated through the gravity potential. The first determining unit is used to determine the target reference station elevation value of the target reference station within the same elevation datum based on the gravity equipotential surface and the target mobile station elevation value. The difference calculation unit is used to calculate the regional elevation datum difference between the target mobile station and the target reference station based on the elevation height of the target reference station and the elevation height of the target mobile station within the same elevation datum if the two remote GNSS observation stations do not transfer elevations within the same elevation datum. The second determining unit is used to determine the elevation value of the target reference station that is not within the same elevation datum based on the elevation value of the target reference station within the same elevation datum and the difference in regional elevation datum.

8. An electronic device, characterized in that, include: The method includes a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer as described in any one of claims 1-4.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer as described in any one of claims 1-4.

10. A computer program product, comprising a computer program, characterized in that, The computer program is executed to implement the method for determining gravity potential and altitude using GNSS carrier phase inter-station single-difference time-frequency transfer as described in any one of claims 1-4.

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